Montgomery, set to make his second career big-league start Monday against the White Sox at home, plopped into the spot and spent three innings talking baseball with Pettitte. It was an experience the 6-foot-6 lefty will never forget.

“It was so cool,” the 24-year-old said Sunday.

Montgomery said he actually didn’t watch much baseball growing up. But when he did, he liked guys like Jon Lester and Pettitte — tall southpaws who had plenty of success. They built at least part of their lengthy resumes attacking right-handed hitters inside, something in which Montgomery takes great pride.

So, you could guess what Montgomery talked to Pettitte about.

“I was just picking his brain,” the South Carolina native said. “Just about how he pitched, how he went about his business.

“He had so much success over such a long time with the Yankees. So I was just trying to learn as much as I could. He’s one of the legendary Yankees. I wanted to learn.”

Montgomery said he found Pettitte approachable and welcoming.

“I had heard a lot about him, how good of a guy he was,” the young pitcher said. “That took the pressure off.”

In Montgomery’s first start after being named the Yankees’ fifth starter, he impressed manager Joe Girardi. Montgomery pitched just 4 1/3 innings, but he struck out seven and the Yankees snatched an 8-4 victory.

Girardi said he knew how Montgomery could improve this time around, however.

“I think fastball command needs to improve for him,” Girardi said. “But I’m not surprised it wasn’t great considering it was his first day he ever pitched in the big leagues. I think his slider will be better. I think that’s a big pitch for him.”

Girardi said it was tough for him to come up with a comparison for Montgomery, who uses an awkward straight-over-the-top arm slot to deceive hitters. Girardi offered up Chuck Finley, who was also 6-foot-6. Finley pitched 17 seasons in the bigs.

When asked if Montgomery reminded him of Pettitte at all, Girard wasn’t totally convinced.

“His stuff is kind of similar,” Girardi said of Montgomery. “Andy used his cutter more. He’s more of a slider and changeup guy.”